Device having automatic process for upgrading the performance of mobile systems

ABSTRACT

To simplify the manufacture of terminals for the use of chip cards, the system is designed so as to place a minimum set of instructions in these terminals and to transfer the storage of complementary instructions pertaining to uses of greater complexity and/or pertaining to the chip card into the chip card. To bring about the performance of these complementary instructions, an address designating an instruction of a complementary set is stored in a reserved memory of the chip card. The microprocessor of the chip card is furthermore provided with a microprogram enforcing the performance of an instruction thus designated as soon as it is detected that the reserved memory has been designated by an instruction of an elementary set of instructions of this microprocessor. It is shown that it is possible, in this way, to simplify and rationalize the manufacture of very powerful terminals.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. Ser. No. 08/546,274, filedOct. 20, 1995, now U.S. Pat. No. 5,687,398, 1997, which is acontinuation application of U.S. Ser. No. 08/233,626, filed Apr. 26,1994, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An object of the present invention is a system of communications betweenan electronic service center and a user by means of an interface. It isdesigned particularly for fields in which access to the interface isconditioned on the presence of an electronic microcircuit of the token,chip carrier, chip card or other type, that is temporarily anddetachably or permanently inserted into the interface. This type ofsystem is found for example with portable telephones that are keptavailable to users but must be barred to persons who have not inserted acorresponding circuit. It also pertains to all payment terminals makingdirect use of chip cards notably in order to bring about cashwithdrawals from bank accounts.

2. Description of the Prior Art

The problem encountered with systems of this type is related to thedefinition of the interface. Indeed, at a given instant, the knownrequirements of safety and comfort of the transaction entail theimplementation of procedures using the interface. These procedure areopen-ended and constantly developing. The consequence or drawbackthereof is that obsolete interfaces need to be changed as and when thesystem develops.

It is possible, nevertheless, to envisage the updating of the interfaceoperation systems in a manner similar to that used to update operatingsystems in microcomputers. However, the drawback of this method is thatseveral updating operations have to be carried out. Furthermore, theowner, or manager, of an interface is not its user, i.e. the person whopossesses the authorizing electronic circuit in question. For example,for a terminal enabling payment by chip cards in a restaurant, the ownerof the interface is the restaurant-owner while the user or payer is thebearer of the chip card. This is also the case with portable telephonesystems, notably in the field of rented cars in which the portabletelephone (and hence the interface) belong to a car rental firm (or to atelecommunications network utility company) and where the chip card orelectronic circuit concerned belongs to the user. In this case, adifference in updating, from one interface to another, may make the usevery complicated for a user.

There is a necessary gap between the wishes of the user whose interestlies in obtaining access, with his card, to the very latest improvementsand the concerns of the interface manager who may be tempted, forreasons of cost, to limit the number of campaigns for updating theinterfaces that he is managing.

A practical example of a need is the one felt in the field of portabletelephones where the interface manager or else the owner of theelectronic service center would like to be able to count down prepaidunits in users' chip cards, somewhat as is done for public telephones.Now, in present-day portable telephone sets, the interfaces are notprovided, in their operating system, with a set of instructions thatenables this countdown or reverse counting operation. This will be thecase at a later date. The problem to be resolved in this particularcase, therefore, is that of carrying out a countdown in the chip card,with an interface that is not provided with means for this purpose, ofthe countdown pulses that would be sent by a telephone electronicservice center. The difficulty of the problem can clearly be seen.

An object of the invention is to find a solution to this problem and topropose far greater flexibility of use of the interfaces or operatingterminals. Several approaches may be envisaged. It is possible, notably,to define a "universal" mechanism that enables the terminals to bemanaged transparently from the electronic service center. For thispurpose, it would be necessary to equip every existing terminal withthis new mechanism. This approach is therefore an unrealistic one. Theapproach envisaged in the invention does not call for any modificationof the terminal, and only uses resources of this terminal that arealready available. These resources are either procedures available fromthe electronic service center or card instructions (these cards beingfitted into the terminal) controlled from the electronic service centerthat enable data elements to be conveyed through the terminal up to thecard. Furthermore, according to the invention, these terminals willthemselves have the simplest possible operating system which,ultimately, will not even need to be constantly updated.

The idea of the invention entails the use, in the operating system ofthe interfaces, of a minimum set of instructions or even an existingprocedure from the existing set of instructions. This set or thisprocedure is used to cause the designating, in a reserved zone of thememory of the chip, of an instruction of a complementary set, orextended set. This complementary instruction is then carried out eitherby the microprocessor of the chip card or by the microprocessor of theinterface, these microprocessors acting on the designated peripherals.They prompt, for example, a display of information elements on a screenof the interface, a counting down of prepaid units in a memory of thechip card, a dispatching, to the electronic service center, of a reportrelating to the chip card and/or to the call in progress (notably forpurposes of billing related to transmission times) or an invalidation ofthe chip card, etc.

With the existence of a reserved zone whose place and use are known, itis thus possible, with the minimum set of instructions of the interfaceoperating system, to load the characteristics of an instruction. Thecharacteristics of this instruction are either the instruction code ofthis instruction itself or an address of this instruction in a memory ofthe chip. In addition to this reserved zone, the microprocessor of thechip card contains an automatic process for carrying out the instructionwhose characteristics have been loaded into the reserved zone. As soonas it is sought to increase the utilization capacity of a system, thecharacteristics of the instruction to be carried out are sent to thechip from the electronic service center. They are transmitted naturallyby the interface. Since this interface is capable in practice ofselecting and writing (this is a minimum) in a memory zone in the memoryof the chip card, it can write the characteristics of this instructiontherein. Subsequently, the microprocessor of the chip card takes overthe operation in order to bring about the performance of thisinstruction with its automatic process.

In one improvement, rather than sending the instruction from theelectronic service center, additional instructions will be loaded intoupdated chip cards, in additional sets of instructions. In this case,the characteristics of instructions to be sent by the electronic servicecenter consist only of a designator, designating that one of theinstructions which is to be carried out.

As a variant, an existing procedure is used to manage the card that isassociated with the sending of a data element. A data element is given aparticular form and, at reception in the card, it is ascertained thatthe data element has this particular form. If desired, an instruction ofthe extended set of instructions is carried out, and this instructionthen corresponds to this particular data element.

SUMMARY OF THE INVENTION

An object of the invention, therefore, is a communications systemcomprising:

an electronic service center, an electronic chip borne by a chip cardand a communications interface between this electronic service center,this chip and possibly a user;

in the interface, a microprocessor and a program memory provided with alimited set of instructions or procedures of communication with thechip, and

in the chip, a microprocessor and a program memory also provided with acorresponding limited set of instructions or procedures,

wherein the chip comprises

a reserved memory zone in which, during a session of use, theinstructions or procedures of the chip and/or of the interface are usedto select or write the characteristics of an instruction different fromthose of the limited sets or procedures, and

an automatic process for the carrying out, during this session of use,of this different instruction after its characteristics have beenselected or written in this reserved memory zone.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood more clearly from the followingdescription and from the figures that accompany it. These figures aregiven purely by way of an indication and in no way restrict the scope ofthe invention. Of these figures:

FIG. 1 shows a general view of a communications system according to theinvention;

FIG. 2 shows a schematic view of the operation of the automatic processfor carrying out the instruction of the complementary set;

FIG. 3 shows typical microprograms implemented in a chip card workingwith the communications system of the invention.

MORE DETAILED DESCRIPTION

FIG. 1 shows a communications system according to the inventioncomprising an electronic service center 1, an electronic chip 2 that isborne, for example, by a chip carrier 3 such as a chip card or achip-based token or any other carrier, notably an integrated circuitconnection carrier in its DIP(Dual In-line Package) or SMC(SurfaceMounted Component) pack. This system also has a communications interface4 between this electronic service center 1, this chip 2 and possibly auser who may manipulate control buttons 5 of the interface 4. Theelectronic service center 1 is the system that houses the applicationand makes it available to numerous interfaces and users. The electronicservice center 1 sends information elements to the interfaces as well asto the card by means of a transmission link 6. There may, however, be adirect connection. The transmission link 6 may also be a path in a datatransmission network and may take many forms: it may be a wire link, aRF link etc. It uses a transmission protocol and notably modems 7 and 8to convey information elements. These information elements representdata elements, addresses and/or instructions.

The interface 4 may be dedicated to an application, for example of theEFTPOS (Electronic Found Transfer Point Of Sale) type or it may be astandard interface, for example of the type used with personal computersor with the Minitel system. The role of the interface essentially is toenable a user to enter into dialog with the electronic service center 1or the chip 2 and/or to convey and shape information elements sent tothe electronic service center 1, the chip 2 or the interface 4. The chipcard 3 has data elements proper to the application and proper to thebearer (i.e. the user). It has an operating system that offers a fullrange of functions by means of a set of instructions which are mostlyspecific instructions.

In the interface 4, there is installed a microprocessor 9 connected, bymeans of a control, data and address bus 10, essentially to a programmemory 11, a chip-carrier reader 12 and an input/output circuit goingtowards the electronic service center 1, for example the modem 8. Inthis minimal version, the interface 4 is used only to ensure trafficwith the chip card 3. If need be, the bus 10 is also connected to adisplay screen 13 used to display the operations carried out.Preferably, the bus 10 is also connected to control buttons 5 enablingaction by a user. In this case, the interface is an interface betweenthe operator and the chip card or among the electronic service center,the operator and the chip card. The program memory 11 has a limited setof instructions, in this case the instructions SELECT, READ, UPDATE,STATUS, which are few in number. In practice, the only essentialinstructions are the instructions SELECT and UPDATE which respectivelyenable the selection of a memory zone of the memory of the chip cardand/or the writing of information therein. However, for reasons ofcomfort, this limited set will also include solely a read-onlyinstruction READ for the reading of a zone of the chip card and,preferably but not necessarily, an instruction STATUS that can be usedto send information on the status of the counters or internal registersof the chip cards to the electronic service center and/or to displaythem on the screen 13. The content of this instruction is still to bedefined. It could also be a Joker type of instruction.

The chip 2 of the card 3 has a microprocessor 14 and a program memory 15comprising at least one limited set of instructions 16. The set 16corresponds to the set 11 and contains the same instructions as this set11, i.e. the instructions SELECT, READ, UPDATE and STATUS. Here too, itis only the instructions SELECT and UPDATE that are essential to theimplementation of the invention. It will be noted that the limited sets11 and 16 may be a little more extensive than these minimum sets. Thechip 2 also has a bus 17, which is of the same type as the bus 10,linking up the microprocessor 14, the program memory 15 and aninput/output device 18. In the case of the chip cards, this input/outputdevice has a standardized connector whose metallic regions are designedto come into contact with the feelers 19 of the reader 12.

One of the essential characteristics of the invention is that the chip 2has a reserved memory zone 20 linked by the bus 17 to the microprocessor14. In this reserved zone 20, the electronic service center 1 promptsthe writing of characteristics of an instruction different from that ofthe limited sets of instructions 11 and 16. It prompts, for example, awriting of the characteristics of an instruction REPORT (different fromSTATUS) tending to make the microprocessor send a status report, to thescreen 13, on the balance of prepaid units contained in an auxiliarymemory 21 of the card. This different complementary instruction may alsobe an instruction ALGO tending to make the microprocessor 14 carry out amessage-enciphering algorithm or an algorithm for authenticating thechip card 3 of the terminal 4. This different instruction may also be aninstruction CHANGE for changing the value of the prepaid units in orderto obliterate certain units 22 in accordance with the duration of thecall. It may also be an instruction INVAL to disable or invalidate thecard, or any other instruction whose need will gradually become felt asand when the applications themselves develop.

What is stored in the reserved memory zone 20 is not the characteristicsof an instruction different from that of the limited set ofinstructions, but rather an address relating to the storage of aninstruction of a complementary set of instructions in a complementarypart 23 of the program memory 15 (or of another memory of the chip 2).This mode is preferred because it is enough to make the electronicservice center 1 send only the address, in the complementary part 23 ofthe program memory 15, of the different instructions that have to becarried out: REPORT, ALGO, CHANGE, INVAL, etc. This is shorter. FIG. 2shows the operation of the preferred automatic process for theperformance of the different instruction after it has been selected orwritten. In this figure, the same elements are designated by the samereferences as in FIG. 1. The invention is especially valuable when thepair constituted by the interface 4 and the chip 2 must be made to carryout an instruction that is not already in the limited set ofinstructions 11 or 16. In the following description, the serial orparallel character of the transmission of the various informationelements shall not be taken into account. Indeed, the necessary matchingoperations are carried, firstly, by the MODEM 8 and, secondly, for theknown protocols for the management of chip card memories, by the readers12.

A message 24 is sent out by the electronic service center 1. Itessentially comprises a first part 25 relating to an instruction code, asecond part 26 relating to a designated memory zone (the zone to whichthe instruction pertains) and a part 27 relating to a data element. Thepart 27 may have a fixed or variable length and, in this case, in aknown way, it has, by way of a header in binary mode, a byte indicatingthe length of the information element transmitted.

In a first example, the instruction will be a SELECT instruction, andthe concerned memory zone will be the reserved memory 20 whose addressis MEM RES, and the data element will relate to the characteristics ofan instruction, for example ALGO. The microprocessor 9 of the interface4 receives this message 24 and transmits the instruction contained inthe zone 25, the address contained in the zone 26 and the data elementcontained in the zone 27 respectively on its control bus 28, address bus29 and data bus 30. This transmission is sent to the microprocessor 14,according to known protocols and by means of the reader 12 and theconnector 18. The microprocessor 14 then carries out the instruction,SELECT for the message 24 or UPDATE for a message 31, starting with theloading of this instruction into its instruction register 32. Theconcerned instruction is then carried out by the microprocessor 14 whichrespectively selects or updates the reserved memory 20. To this end, theselection address MEM RES is transmitted by an address bus 33 of themicroprocessor 14. A command resulting from the execution of the SELECTor UPDATE instruction is applied, by means of a control bus 34, to acircuit 35 for the management of the memory 20. The circuit 35 is quitesimply a read/write circuit so that it can carry out operations for thereading or writing, in the memory 20 at addresses conveyed by the bus33, of data elements conveyed by a data bus 36. The data bus 36transmits the data elements received from the bus 33. In the case of themessage 31, the microprocessor 14 makes the circuit 35 carry out arecording, namely an operation of writing, in the memory 20 of themessage ALGO received from the electronic service center 1. It isobserved here that the fact of writing in the reserved memory is in noway different from that of writing in another part of the memory of thechip 2. This is a common type of command. The automatic process of theinvention is designed for the transmission, in the instruction register32 of the microprocessor 14, of the different instruction whosecharacteristics have thus been stored in the reserved memory 20.

In practice, in a preferred version, what has been stored in the memory20 is not the instruction itself but an address of an instruction in thecomplementary set of instructions 23. Hence, after the recording of thecharacteristics, of the address, of the designated complementaryinstruction, ALGO, the content of the memory 20 is used to serve as anaddress and to designate one of the instructions of the program memory23. In other words, in the preferred automatic process, themicroprocessor 14 reads the memory 20 and transmits the data read to itsaddress bus 33. This address designates a memory zone of the programmemory 23. Once this designating has been done, the microprocessorcarries out a reading, in the designated memory zone, of the dataelement that is stored therein. This data element is in fact thedifferent instruction. The microprocessor then transmits it by itscontrol bus 34 to its instruction register 32. The microprogram of theautomatic process ends with a performance of the different instructionthat has been thus loaded.

The object of this different instruction may be to modify the content ofan auxiliary memory 21 of the chip 2. This different instruction mayalso be transmitted, in the reverse direction, to the microprocessor 9and may be applied to the interface 4 for display on the screen 13 oranother such device. It may also be implemented directly, by means ofthe microprocessor 14, to modify the content of certain memories orperipherals of the interface 4. However, in view of the preferredchoices of protocols, which are respectively series and parallelprotocols, for a chip card 3 and an interface 4, it is preferred todelegate the implementation of the different instruction to themicroprocessor 9. This instruction is therefore loaded into aninstruction register of the microprocessor 9, in the same way as for themicroprocessor 14.

FIG. 3 shows a preferred operation of a microprogram pre-recorded in aprogram memory 16 of a chip card liable to implement the communicationssystem of the invention. At the beginning of this microprogram, themicroprocessor 14 is in a state of awaiting the reception of aninstruction. Then, it receives an instruction transmitted by the bus 28.First of all, it ascertains that this instruction is a selectioninstruction during a step 37. If this is the case, it carries out theselection of the memory zone, which is the designated memory 20 ormemory 21. If not, during a step 38 the microprocessor carries out atest to find out whether the instruction is a reading instruction READ.If this is so, it prompts the reading of the memory zone whose addressis contained in the part 26 of the message. If not, in a step 39 itfinds out whether the instruction is an updating instruction and, ifthis is the case, it updates the concerned memory zone. Finally, thereis normally no longer any test to be planned, and the remaininginstruction should be a STATUS instruction since, in principle, the onlyinstructions that the microprocessor is liable to wait for are theinstructions of the limited set of instructions.

It can be seen that it is possible to provide for a larger limited setof instructions or, if necessary, for a smaller limited set ofinstructions. Only the SELECT and UPDATE instructions are trulyindispensable for the method of the invention. Thus, in a step 40, themicroprocessor 14 will ascertain that the instruction received is arequest for preparing a STATUS report and, if necessary, it carries outthis instruction. It must be noted that the STATUS instruction could bea standardized instruction without, in principle, carrying anydesignation of a memory zone in the zone 26 of the message.

If, on the contrary, during the tests 37 to 40, the microprocessor 14has not detected the fact that an awaited instruction has beenrecognized then, in an operation 41, it delivers an error message (whichmay be displayed for example on the screen 13, but not necessarily so).During an operation 42 following the execution of each of theinstructions SELECT, READ, UPDATE and possibly STATUS, themicroprocessor 14 seeks to find out whether the address contained in thepart 26 of the message was an address MEM RES of the reserved memory. Ifthis was not the case, the microprocessor 14 assumes that the processingof the message has been completely carried out. It returns to a standbyor waiting state. As for the STATUS instruction, the system could bedesigned so that the microprocessor 14 returns systematically to a stateof waiting for instructions, or else provision could be made forcarrying out the test 42 if the zone 26 of the message has been writtenin.

Should the zone 20 of the reserved memory be concerned, themicroprocessor 14 loads the address bus 33 with the content of thismemory. The address bus 33 then designates one of several addresses ofthe complementary memory 23. Depending on whether the bus 33 designatesthe first, second or another address of the memory 23, it is possible,with a cascaded battery of tests 43, 44, to prompt the selection, in thememory 23, of one out of several instructions. The instructions have tobe stored in the control register 32 of the microprocessor. 14.Preferably, the memory 23 will be a non-volatile type of memory, withmemory cells comprising floating-gate transistors, preferably of theelectrical erasable programmable (EEPROM) type. In this case, after themicroprocessor 14 has been made to carry out the complementaryinstruction, the erasure of the reserved memory is brought about so thatthis reserved memory is again blank. The erasure step 45 is thus carriedout, in this way, after the complementary instruction has been carriedout.

It is possible, however, to carry out a different procedure. It ispossible, for example, to design the system so that the updatinginstruction UPDATE carried out by the microprocessor 14 (and not by themicroprocessor 9) itself comprises a microprogram consisting of thepreliminary erasure of the reserved memory 20 before the recording of anew designator with a view to the execution of another complementaryinstruction. This is useful when it is necessary to prompt the countingdown of units in the memory zone 21 of the chip card 3. Indeed, in thiscase, at the first transmission, the electronic service center 1 sendsan instruction UPDATE relating to the designating of an instruction forcounting down units in the complementary zone 23. Subsequently, all thatit needs to do is to select the reserved memory so that the the unitsmay be counted down automatically. Indeed, the countdown instruction isalready recorded in the memory 20, and it is not necessary to rewriteit. It is enough to select it, read it and go through the step 42. Ifneed be, the instruction STATUS may even be used. The message 31, unlikethe message 24, contains data elements of greater importance in the zone27. These data elements themselves also relate to the reserved memory.They may be stored in different memory zones 46 or 47 of the reservedmemory. In this case, a first part of the content of the message at thezone 27 will be stored in a first zone 46 of the memory 20, a secondpart will be stored in a successive zone 47 and so on in succession.This means that rather than sending all the instructions as and whenthey arise in order to have them carried out by the microprocessor 14,the electronic service center 1 sends only one message containing asequence of instructions that must be carried out sequentially.

In this case, for example, the memory 20 will contain, in each zone, afield 48 and a field 49. In the field 48, there will be stored thedesignators or characteristics of the instructions to be carried out.The field 49 will be, for example, a bit (another system could be used)in which a binary information element will indicate, by the presence ofa "one", that the performance of one instruction of the complementaryset should be followed by the performance of another instruction of thecomplementary set. By contrast, the presence of a zero will indicatethat there are no longer any other instructions to be carried outsubsequently. To this end, the performance of each instruction of thecomplementary set will include, in the microprogram of FIG. 4, a test 50during which it will be sought to find out whether the performance of acomplementary instruction should be followed by a performance of anothercomplementary instruction which may or may not be a followinginstruction. The routing of the microprogram should then be immediate.

One variant uses an existing procedure for the management of the card.For example, an existing procedure for the authentication of the cardcomprises the sending, by the electronic service center, of anenciphered random element to the card, the deciphering of this randomelement by the card, the encryption of a secret code of the card by aDES type algorithm parametrized by the deciphered random element, andthe sending of the encrypted secret code to the reader for verification.In the invention, a given random element, for example 0000XXXX, isreserved, firstly in order to indicate by the 0000 that what is involvedis not truly an existing procedure and, secondly, in order to load thedata XXXX into the memory 20. The rest of the procedure is carried outas described here above. The advantage of using an existing procedurelies in the fact that the (numerous) existing interfaces are alreadycompatible with this procedure. It is enough to insert the test of thepresence of the 0000 into the operating system of the new cards that aremanufactured.

I claim:
 1. A communication system comprising:A. a service center; B. acommunication interface disposed between the service center and anelectronic chip, the communication interface including a microprocessorand a program memory provided with a first limited set of instructionsfor communication with the electronic chip; and C. the electronic chip,mounted on a chip support and including1. a microprocessor,
 2. a programmemory provided with a second limited set of instructions whichcorrespond to the first limited set of instructions,
 3. means forwriting, in a reserved memory zone during a user session using the firstand second limited sets of instructions, the characteristics of adifferent instruction, the different instruction being different thanthose of the second limited set of instructions, and
 4. an automaticexecute system, the automatic execute system executing the differentinstruction during the user session after the characteristics arewritten in the reserved memory zone.
 2. A communication system accordingto claim 1,wherein the communication interface is a portable telephone;wherein the electronic chip in combination with the chip support form achip card which is used to gain access to the portable telephone;wherein the service center includes a first radio frequency modem;wherein the communication interface includes a second radio frequencymodem, the first and second radio frequency modems cooperating to form aradio frequency modem link; and wherein the characteristics of thedifferent instruction are transmitted from the service center to theelectronic chip by way of the radio-frequency modem link and thecommunication interface.
 3. A communication system according to claim1,wherein the program memory of the electronic chip is provided with acomplementary set of instructions; and wherein the characteristicsrelate to an address of an instruction from the complementary set ofinstructions, the address being in the program memory of the electronicchip.
 4. A communication system according to claim 1, wherein theautomatic execute system includesa first microprogram, stored in theprogram memory of the electronic chip, which tests whether a receivedinstruction belongs to the second limited set of instructions, the firstmicroprogram being linked to an execution command for the receivedinstruction; and a second microprogram, stored in the program memory ofthe electronic chip and connected in series with the first microprogram,which tests for a designation of the reserved memory zone by thereceived instruction, linked to an execution command for the differentinstruction.
 5. A communication system according to claim 1 wherein theautomatic execute system includes a microprogram, stored in the programmemory of the electronic chip, which tests for a designation of thereserved memory zone, linked to an execution command for the differentinstruction.
 6. A communication system according to claim 1,wherein theprogram memory of the electronic chip is provided with a complementaryset of instructions; wherein the characteristics relate to an address ofan instruction from the complementary set of instructions, the addressbeing in the program memory of the electronic chip; and wherein theautomatic execute system includes the following microprograms, stored inthe program memory of the electronic chip,a first microprogram whichtests whether a received instruction belongs to the second limited setof instructions, the first microprogram being linked to an executioncommand for the received instruction, a second microprogram which testsfor a designation of the reserved memory zone by the receivedinstruction, the second microprogram being connected in series with thefirst microprogram and being linked to the execution command for thedifferent instruction, and a third microprogram which executes theinstruction from the complementary set of instructions, the address ofwhich is stored in the reserved memory zone.
 7. A communication systemaccording to claim 1,wherein the program memory of the electronic chipis provided with a complementary set of instructions; wherein thecharacteristics relate to an address of an instruction from thecomplementary set of instructions, the address being in the programmemory of the electronic chip; and wherein the automatic execute systemincludes the following microprograms, stored in the program memory ofthe electronic chip,a first microprogram which tests for a designationof the reserved memory zone, linked to an execution command for thedifferent instruction, a second microprogram which executes theinstruction from the complementary set of instructions, the address ofwhich is stored in the reserved memory zone.
 8. A communication systemaccording to claim 1, wherein the reserved memory zone of the electronicchip is formed of electrically erasable programmable read only memory.9. A communication system according to claim 1,wherein the reservedmemory zone has a field for storing a piece of information which makesit possible to ascertain that, after the different instruction isexecuted, the execution is to be followed by execution of an additionaldifferent instruction; and wherein the automatic execute system includesa test for verifying the value of the field.
 10. A communication systemaccording to claim 1, wherein the microprocessor of the communicationinterface also executes the different instruction.